The new design of China's passport, which Vietnam and the Philippines have protested because it claims ownership over 90 percent of the East Sea, is not legally significant, a foreign expert says.

Dr. Euan Graham with the S. Rajaratnam School of International Studies told Thanh Nien in an interview via email that the passport design is part of the "ongoing trend" of asserting territorial claims in the waters, internationally known as South China Sea, by Chinese authorities.

"But the design doesn't carry legal weight," Graham said.

It does not make the infamous nine-dash line, which covers about 90 percent of the 3.5 million square kilometer South China Sea on Chinese maps, and which has been included in the passport's design, "any more legitimate in international law," he said.

As any significance to the design is "purely symbolic;" and if Vietnamese and Philippine immigration officers stamp the new Chinese passports, it does not mean that the countries officially accept China's claims, Graham said.

He noted that Taiwanese and Chinese citizens can use their passports as recognized travel documents across the Straits, despite the fact that there are no formal diplomatic ties and China does not recognize Taiwan as a state.

Therefore, "it might be better to avoid actions that are likely to be perceived by third countries as petty retaliation," the expert said.

He warned that "a cycle of retaliation" could lead to travel restrictions imposed by both sides, which would "only penalize individuals, including tourists and business people, who have no say in the matter."

However, Graham also suggested one limited option for Vietnam, if it feels obliged to respond beyond official protests, was to design a specific entry stamp for the new Chinese passports, including a disclaimer or map image to reflect Vietnam's official position.

Meanwhile, Mark Valencia, Hawaii-based expert on the East Sea dispute, said the latest move by China "is clever but risky -- it could backfire if enough countries refuse entry to Chinese nationals with those passports."

On Thursday, Vietnam's Foreign Ministry spokesman Luong Thanh Nghi told a press conference that the ministry's representative has met with representatives of the Chinese embassy in Hanoi to hand over a diplomatic note objecting to the inclusion of the line, demanding that China removes "wrong" content from its passports.

He said by including the nine-dash line in its new passports, China has violated Vietnam's sovereignty over the Hoang Sa (Paracel) and Truong Sa (Spratly) Archipelagos.

It has also violated Vietnam's sovereignty rights and jurisdiction rights over related waters in the East Sea, Nghi said.

Earlier the same day Philippine Foreign Secretary Albert del Rosario also objected to China's new passports, saying that "the Philippines does not accept the validity of the nine-dash line that amounst to an excessive declaration of maritime space in violation of international law," Reuters reported.

Chinese carrying the new passport would be violating the Philippine's national sovereignty, the news agency quoted Philippine foreign affairs spokesman Raul Hernandez as saying.